Expectations have heightened in recent years regarding high-quality, large-screen displays, such as high vision displays. These expectations are being answered with progress in research and development in fields relating to CRTs, liquid crystal displays (LCDs), plasma display panels (PDPs) and so on.
CRTs, which are conventionally used widely as displays in televisions, are superior in terms of resolution and picture quality. However, CRTs are not suitable as large-screen displays of 40 inches or more due to the fact that a larger screen size leads to increased depth and weight.
Furthermore, LCDs, while having the advantage of low power consumption and avoiding the problems of depth and weight, have a limited viewing angle. This is something that must be improved if large-screen LCDs are to be manufactured.
In contrast to CRTs and LCDs, it is relatively easy to make large-screen PDPs even with a shallow depth, and 50-inch class PDPs are already on the market.
A structure such as the 3-electrode surface discharge PDP shown in FIG. 3 is common in conventional PDPs.
The PDP in FIG. 7 is composed of a front panel 101 and a back panel 106 that oppose each other, and a plurality of pairs of parallel display electrodes 103 on the inner surface of the front panel 101. A conductive layer 104 that is a 40 μm-thick low-conductive glass covers the display electrodes 103. An 800 nm-thick MgO film is formed on the surface of the conductive layer 104 as a protective layer 105. The MgO film is generally formed using an evaporation method or a sputter method.
A plurality of ribs 112 and address (data) electrodes 108 are provided parallel to each other on the inner surface of the back panel 106. The ribs 112 separate discharge spaces. The spaces surrounded by neighboring ribs 112 and the protective layer 105 are reserved as discharge spaces. Phosphor 111 that corresponds to one of R, G, and B is applied between neighboring ribs 112.
After being arranged facing each other, the edges of the front panel 101 and the back panel 106 are sealed together. After the discharge spaces are evacuated, a discharge gas is inserted into the discharge spaces. The discharge gas is a compound neon gas that includes some volume percentage of xenon.
In a 3-electrode surface discharge PDP 114 composed as described, voltage is applied to the address electrodes 108 and the display electrodes 103 with an appropriate timing, causing discharge in discharge spaces 115 separated by ribs 112 that correspond to display pixels. This discharge causes the xenon gas to generate ultraviolet rays which excite the phosphor, thus causing the phosphor to discharge visible light. This is how images are displayed.
A surface discharge PDP has the above-described simple structure of two panels sealed together.
However, as a perspective view of the back panel in FIG. 8 shows, the ribs 112 in the conventional PDP having the above-described construction are formed in lines. This means that while the PDP has relatively good evacuation characteristics in the evacuation process of the discharge spaces during manufacturing, there is a limit in the surface area to which phosphor can be applied, and the surface area is not sufficient for improving luminosity.
Recently, various shapes of ribs are being experimented with in order to improve this.
For example, in the example of a perspective view of a back panel shown in FIG. 9, the line-shaped ribs 112 and ribs 113 that intersect with the ribs 112 are positioned so as to enclose the discharge space in each cell individually. Here, the height of each rib 113 is lower than the height of neighboring ribs 112. Providing the ribs 113 in this manner attempts to maintain evacuation characteristics of pairs of neighboring ribs 112, while using the surface of the ribs 113 to increase the surface area of the phosphor.
Another example is one where the ribs composed in a honeycomb shape in which each honeycomb-shaped part is formed by line-shaped ribs and two adjoining ribs. This structure aims to maintain evacuation characteristics in the same manner as the rib structure shown in FIG. 8, while improving luminance by actually increasing the size of discharge spaces (IDW '99 Proceeding of The Sixth International Display Workshops).
However, while substantially sufficient luminosity is ensured in the above-described example, there is scope for improving evacuation characteristics. In other words, even using an idea such as the above-described example, evacuation is still not able to be performed quickly and sufficiently in the evacuation process. As a result, residue that should be removed in the evacuation process builds up in the PDP, causing flickering an the like in images and hindering image display.
For this reason it is necessary to solve this problem as soon as possible.